Opium extract (130211) is a Schedule II controlled substance requiring a DEA import permit and quota authorization. Ephedra extract (130214) is subject to FDA oversight and faces import restrictions tied to its use as a precursor in illicit drug manufacturing. Both require advance authorization well before shipment.

Agar-agar is specifically named in 130231 and covers the gelatinous polysaccharide extracted from red algae. Locust bean gum and guar gum are specifically named in 130232. All other mucilages and thickeners derived from vegetable sources—such as carrageenan, konjac, or psyllium husk—fall under the residual subheading 130239. The botanical source and chemical identity of the thickener determine the correct subheading.